Cops stomped on man at Mardi Gras: sister

Bryn Hutchinson is suing police, claiming he was assaulted at the 2013 Sydney Mardi Gras (file).

The sister of a reveller who was allegedly bashed by NSW police at the 2013 Sydney Mardi Gras has broken down in court while describing how he was "stomped on".

Bryn Hutchinson is suing the police for assault, battery, false imprisonment and malicious prosecution over the March 2 incident, claiming more than $275,000 in damages.

An emotional Kate Hutchinson on Thursday told Sydney's Downing Centre District Court that a group of officers kicked her brother when the 37-year-old tried to cross the famous gay strip, Oxford Street, after the parade ended.

"A bearded officer then came over and stomped on him, punched him and then kneeled on his back," she said.

When her brother complained he couldn't breathe and went red in the face an officer "slammed his head back into the ground".

Ms Hutchinson broke down while describing her attempts to stop the allegedly unprovoked attack.

She said she asked Inspector Clive Ainley why police kept kicking her brother, to which he responded: "I'm not looking."

Court documents from the civil trial show the officers claimed the four blows they struck were necessary and lawful to stop the man from crossing the street.

Mr Hutchinson was charged with assaulting and resisting an officer over the incident but a judge later dismissed the charges.

The gay rights activist claims his head was punched into the pavement in a brutal, unwarranted and excessive attack, which left him humiliated and with bruises all over his body.